One hour of exercise a week can prevent depression

A landmark study led by the Black Dog Institute has revealed that regular exercise of any intensity can prevent future depression — and just one hour can help.
Published in the American Journal of Psychiatry, the results show even small amounts of exercise can protect against depression, with mental health benefits seen regardless of age or gender.
This most extensive and largest study involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years.
The international research team found that 12 percent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week.
“We’ve known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression,” said lead author Associate Professor Samuel Harvey from Black Dog Institute and UNSW.
“These results highlight the great potential to integrate exercise into individual mental health plans and broader public health campaigns. If we can find ways to increase the population’s level of physical activity even by a small amount, then this is likely to bring substantial physical and mental health benefits.”
A healthy cohort of participants was asked at baseline to report the frequency of exercise they participated in and at what intensity: without becoming breathless or sweating, becoming breathless and sweating, or exhausting themselves. At follow-up stage, they completed a self-report questionnaire (the Hospital Anxiety and Depression Scale) to indicate any emerging anxiety or depression.
The research team also accounted for variables which might impact the association between exercise and common mental illness. These include socio-economic and demographic factors, substance use, body mass index, new onset physical illness and perceived social support.
Results showed that people who reported doing no exercise at all at baseline had a 44% increased chance of developing depression compared to those who were exercising one to two hours a week.
However, these benefits did not carry through to protecting against anxiety, with no association identified between level and intensity of exercise and the chances of developing the disorder.